HTTP Request ParametersΒΆ

When Dydra processes a query request, it combines the algebra expression which it generates from the query text with several bits of metadata which it extracts from the protocol request or gathers from the request repository and system configuration.

Some of the properties are specified in the standards for the SPARQL language and request protocols. Others are specific to Dydra’s processing interface. Some are implicit in the standards, but no means is described to include them in a request. This document describes how to set these properties, either for individual queries or for all processing for a repostiory or an account, how these settings interact, and how a given effective setting affects the query processing.

The following properties govern query execution

parameter request protocol request text repository configuration account configuration system configuration

access authentication key :

  • authentication-key. api-key (string)

base iri :

  • base-iri (iri)
URL BASE yes yes yes

dataset :


describe form:

URL PREFIX yes yes yes

dynamic binding :

  • $variable=value

entailment mode :

  • entailment-ruleset, ruleset (iri list)
URL PREFIX yes yes yes

federation mode :

  • federation, federation-mode (urn):

  • authorized-client-locations (iri, repository only)

  • authorized-service-locations (iri, repository only)

URL PREFIX yes yes yes


  • property-index (list string iri)
yes yes yes

processing bounds:

  • memory-limit (integer)
  • solution-limit (integer)
  • time-limit, timeout (integer)
URL PREFIX yes yes yes

provenance mode :

  • provenance-repository-id (string)
URL PREFIX yes yes yes

repository id:

  • repository-id (string)
  • revision-uuid (string)

response bounds :

  • limit, response-limit (integer)
  • offset, response-offset (integer)
URL PREFIX yes yes yes

response content type :

accept, response-content-type

revision id :

  • revision-uuid (string)

skolemization mode :

  • skolemize (urn) :
  • skolemize-prefix (string)
URL PREFIX yes yes yes

undefined variable behavior :

  • undefined-variable-behavior (urn) :
URL PREFIX yes yes yes

user query id :

  • user-tag (string)

xslt style sheet :

  • xslt (iri)

As these parameters may be specified in a number of ways, the Dydra query processor combines the values to produce the setting in effect for a given request. For those parameters which can be specified in the request, for example, the request dataset, the SPARQL protocol, requires that the protocol request values supercede any values present in the query text itself. Dydra applies the same rule to all parameters and, as an extension, supercedes any configuration values with those from the request. Among the configuration parameters, repository settings supercede those of the respective account, which supercede those of the system. In the case of a limit, however, no more specific value may increase the value beyond that of a more general setting.

When a request specifies a stored query, these precedence rules apply directly, as that stored query text is processed as if it were included in the request.

When, on the other hand, the processor caches queries, the cached instance entrains several of the original effective parameters in its compiled form. As a consequence, when the query is re-executed - whether by intent with new variable bindings or implicity, any compiled-in variations remain unaffected by any properties which change in the subsequent request. This is the case for the follwing parameters.

  • repository-id : a repository’s term and statement statistics affect pattern suppression and reordering and solution propagation.
  • dataset: iff a dataset was specified, the respective complement may be changed.
  • entailment mode : any applicable rules are compiled into the bgp interpretation.
  • federation mode : the mode determines sub-selects generated for implicit internal and explicit external cross-references.
  • base-iri: any initial base iri is used to expand qname terms when the query text is parsed.
  • undefined-variable-behavior: the mode determines the mechamism generated to interpret free variable references.

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